Control content transmission method and streaming broadcasting system

ABSTRACT

An object of the present invention is to provide a non-storage type broadcasting system for automatically providing the user with a presenter required for viewing a desired content with a viewer. In a non-storage type broadcasting system ( 100 ) for providing a user interface (B) unique to each (Sm) service (S), transmission means ( 110 ) sends out a control content (Cb), which implements the user interface (B), as part or whole of the content, and reception means ( 130 ) receives the sent control content (Cb) and activates the received control content to execute the user interface.

TECHNICAL FIELD

The present invention relates to a non-storage type information servicesystem which automatically provides the user in real-time with apresenter required by the user to view desired content with a viewer,regardless of the presence or absence of the user's request, and morespecifically to a non-storage type broadcasting system whichautomatically updates a viewer.

BACKGROUND ART

In an information service system, which provides users with a contentviewing service, a browser is required for supplying content data to beprovided to a presenter which is an input/output device allowing theuser to access it through a physical phenomenon. This browser isrequired to be appropriately updated, as necessary, in accordance withfactors such as content data to be presented, a transmission paththrough which the content data is provided to the user, and the user'sbrowser.

Examples of a conventionally implemented information service systeminclude push-type information delivery services on the Internet, such asPointCast(R) PointCast Network(R) and Microsoft (R) Active Desktop(R),which involve the use of computers.

The push-type information delivery service can be classified into astorage type and a non-storage type. In the push-type informationdelivery service of the storage type, content, such as news or a weatherforecast, which is broadcast by a broadcast station on the Internet, isreceived and stored by a reception device on the user side, e.g., apersonal computer. In the push-type information delivery service of thenon-storage type, content, such as news or a weather forecast, which isbroadcast by a broadcast station on the Internet, is received by areception device on the user side, e.g., a personal computer, andpresented to the user in real-time. The user operates the receptiondevice so as to activate the browser, which is a user interface forseeing the content, and thus can view the content stored in the receiverregardless of the storage type or the non-storage type.

Since different content processing methods are used for differentservices, the browser varies from one service to another. Therefore, itis possible to realize a user interface which is flexibly compatiblewith each service. If the browser is required to be upgraded, the useruses a function programmed to the browser itself to receive a newbrowser. Then, the current browser can be updated to the latest versionby replacing it with the newly received browser.

Referring to FIGS. 24, 25, 26, 27, 28, 29, and 30, an exemplaryconventional broadcasting system is described. As shown in a blockdiagram of FIG. 24, a broadcasting system 2500 includes a transmissiondevice 2510, a transmission path 120, and a non-storage type receptiondevice 2520. The transmission device 2510 includes browser storages2511, browser senders 2513, content storages 1113, content senders 2514,a multiplexer 115, and a sender 116.

A plurality of each of the browser storages 2511, the browser senders2513, the content storage 1113, and the content senders 2514 areprovided, and they are distinguished from each other by assigning asuffix (a lower-case alphabetic character) to their respective symbols.In the following descriptions, if a plurality of elements of the sametype are present, they are distinguished from each other similarly byassigning a suffix to their respective symbols. Note that if there is noneed to individually distinguish them, they are referred to by theirrespective generic names without assigning a suffix to their symbols.

In the example shown in FIG. 24, there are provided three of each of thebrowser storages 2511, i.e., 2511 a, 2511 b, and 2511 c, the browsersenders 2513, i.e., 2513 a, 2513 b, and 2513 c, the content storages1113, i.e., 1113 a, 1113 b, and 1113 c, and the content senders 2514,i.e., 2514 a, 2514 b, and 2514 c. Note that if there is no need toindividually distinguish them, they are referred to by their respectivegeneric names, such as the browser storages 2511, the browser senders2513, the content storages 1113, and the content senders 2514.

FIGS. 25, 26, 27, and 28 show how data is stored in each element of theabove broad casting system 2500. The browser storage 2511 individuallyexists for each service. Three individual browser storages 2511 a, 2511b, and 2511 c are respectively provided for three services (S1, S2, andS3). The browser senders 2513 store browsers B corresponding to services(S) to be provided to the user, and send the browsers B to themultiplexer 115 according to a predetermined schedule.

The browser sender 2513 a corresponding to the service S1 has a browserB(S1) stored therein. The browser B is a computer program written innative code (machine language) of a CPU (central processing unit) of thenon-storage type reception device 2520. Similarly, the browser sender2513 b corresponding to the service S2 has a browser B(S2) storedtherein, and the browser sender 2513 c corresponding to the service S3has a browser B(S3) stored therein. Note that the generic name “browserB” is used unless there is no need to distinguish their details.

A specific method for sending a browser, such as a transmission protocolor a transmission schedule, is uniquely defined for each service.Accordingly, the details of processing by the browser senders 2513 varyfrom one service to another. Therefore, the browser senders 2513 a, 2513b, . . . 2513 n (where n is an arbitrary natural number) individuallyexist for their respective services.

In the example shown in FIG. 24, three individual browser senders 2513a, 2513 b, and 2513 c correspond to three services S1, S2, and S3. Thecontent storage 1113 stores content C belonging to a correspondingservice. The content storage 1113 individually exists for each service.Three individual content storages 1113 a, 1113 b, and 1113 c arerespectively provided for three services.

In the example shown in FIG. 25, the content storage 1113 acorresponding to the service S1 has stored therein two service contentsC(S1,1) and C(S1,2). The content storage 1113b corresponding to theservice S2 has no content C stored therein. The content storage 1113 ccorresponding to the service S3 has stored therein service contentsC(S3,1), C(S3,2), and C(S3,3). Note that the generic name “servicecontent C” is used as above unless there is no need to distinguish theirdetails.

Referring back to FIG. 24, the content sender 2514 uses a predeterminedmethod to send to the multiplexer 115 content C(Sm,O) stored in thecontent storage 1113 associated with a corresponding service. Note thatin content C(Sm,O), Sm is a combination of symbol S representing aservice, and a suffix m (an arbitrary natural number) assigned theretofor distinguishing individual services, while O (an arbitrary naturalnumber) indicates the position in a sequence of a plurality of contentsC belonging to service Sm.

In the sending device 2510 used in the conventional broadcasting system2500, a method for sending a browser or content varies from one serviceto another. Accordingly, it is necessary to provide a plurality ofindividual browser senders 2513 and a plurality of individual contentsenders 2514 for their respective services. Further, browser B andcontent C are different in how they are sent. Accordingly, also forbrowser B and content C, it is necessary to provide an individualbrowser sender 2513 and an individual content sender 2514.

The multiplexer 115 multiplexes and modulates a browser B outputted fromthe browser sender 2513 and service content C(Sm,O) outputted from thecontent storage 1113 together into a form suitable for sending, andoutputs a digital bit stream. The multiplexer 115 may consist of amultiplexing device and a modulation device in a digital broadcaststation system.

The sender 116 sends a result of processing by the multiplexer 115 tothe transmission path 120. A modem can be used as the sender 116 if thetransmission path is a wired communication line. Alternatively, if thetransmission path is a broadcasting communications satellite and outerspace, a parabolic antenna for sending may be used as the sender 116.

Next, the transmission path 120 is described. The transmission path 120is a means for transmitting, to the non-storage type reception device2520, information such as content, a browser, etc., which is sent fromthe sending device 2510. For example, the transmission path may be anoptical fiber, a cable of any type, a broadcasting communicationssatellite and outer space, or a package medium such as a DVD and adistribution channel thereof.

Next, the non-storage type broadcasting system is described in detail.The non-storage type reception device 2520 includes a receiver 131, ademodulator/separator 132, a storage 133, a renderer 134, a presenter135, an input device 136, a CPU 137, and a memory 138.

The receiver 131 receives information such as content C, browser B,etc., which is sent to transmission path 120, and outputs a digitalstream. The receiver 131 may be a modem or a combination of an antennaand a module for an ordinary digital broadcast receiver.

The demodulator/separator 132 demodulates the digital bit streamoutputted from the receiver 131, and separates multiplexed information.The demodulator/separator 132 carries out a process opposite to aprocess carried out by the multiplexer 115 of the sending device 2510.The outputs of the demodulator/separator 132 are supplied to the storage133 and the renderer 134, and can be read by the CPU 137.

Among the browser and the content outputted from demodulator/separator132, the storage 133 stores only the browser. This is because thenon-storage type reception device 2520 displays, in real-time, thecontent C sent from the sending device 2510 and thus are not required tostore the content C, while the browser B for presenting deliveredcontent C has to always be prepared. The storage 133 is composed of, forexample, a randomly accessible storage medium, such as a hard disk. Thecontents of data stored in the storage 133 can be read and changed bythe CPU 137.

As shown in FIG. 26, the storage 133 has stored therein a total of threebrowsers B(S1), B(S2), and B(S3) which are supplied from thedemodulator/separator 132. Note that the demodulator/separator 132 mayoutput only the browser B to the storage 133, while thedemodulator/separator 132 may output only the content C to the renderer134.

In response to a request from the CPU 137, the renderer 134 renders OSD(on-screen display) and content, which is inputted from thedemodulator/separator 132, into graphics that are to be displayed on thescreen.

The presenter 135 presents graphics and/or audio, which are outputtedfrom the renderer 134, in forms that are viewable/audible to the user.The presenter may be a CRT display, for example.

The input device 136 is a means operated by the user to provide theuser's instruction to the non-storage type reception device 2520. As theinput device 136, a combination of a remote control and a lightreception portion of the remote control, a keyboard, a mouse, or thelike can be used.

The CPU 137 is a central processing unit which is interconnected to eachelement of the non-storage type reception device 2520, and operable toexecute a computer program stored in the memory 138 to control theentire non-storage type reception device 2520.

The memory 138 is composed of a RAM/ROM which is arewritable/non-rewritable semiconductor memory, and used as a region forstoring data of processing by the CPU 137 or a computer program or datathat is to be executed by the CPU 137. As illustrated in FIG. 27, thememory 138 has stored therein a browser list 2700 and an execution form2651 which is native code (machine language) of the CPU 137.

Next, referring to FIG. 28, the browser list 2700 is described. Thebrowser list 2700 is information in the form of a table which has a rowfor each service and having a column 2710 for browser file names and acolumn 2720 for service names. The browser list 2700 is used to make itpossible to identify a browser used for utilizing a desired service fromamong information outputted from the demodulator/separator 132.

Next, referring to a flowchart shown in FIG. 29, a principle operationof the non-storage type reception device 2520 is described in detail.

At step S2801, service names in the browser list 2700 stored in thememory 138 are listed on the screen. The display onto the screen iscarried out by the renderer 134.

At step S2802, it is detected based on the user's operation of the inputdevice 136 that a service has been selected from the list displayed atstep S2801.

At step S2803, for the selected service detected at step S2802, the filename column of the browser list 2700 is referenced for browser B toidentify the file name B(Sm) of the browser B in the storage 133.

At step S2804, the file B(Sm) identified at step S2803 is executed. Thebrowser is written in the native code of the CPU 137, and therefore canbe directly executed by the CPU 137.

Next, referring to a flowchart shown in FIG. 30, a process performed bythe non-storage type reception device 2520 for updating a browser isdescribed.

At step S2901, browser B is activated by the CPU 137.

At step S2902, the receiver 131 and the demodulator/separator 132receive browser B that is currently being sent out from the sendingdevice 2510, and check the version thereof.

At step S2903, if it is determined that the browser B received andchecked at step S2902 is of a newer version than the browser B that iscurrently being executed, the procedure proceeds to the next step S2904,and if not, then the procedure is terminated.

At step S2904, the non-storage type reception device 2520 receives thebrowser B that is being sent out, and the storage 133 temporarily storesthe received browser B as a file as illustrated in FIG. 26.

At step S2905, the browser B that is being executed is replaced with thefile that is being temporarily stored. Then, the browser B isreactivated to start executing the received new version of browser.

As a specific method for transmitting a browser which is a computernative code, the above-illustrated conventional broadcasting system usesa unique method which is different for each service. Accordingly, boththe sending and reception devices are required to implement anindividual method which is different for each browser which varies fromone service to another.

That is, in the sending device, it is necessary to provide a differentbrowser sender for each service. Also, in the reception device, the codeof a browser of each service itself is typically programmed with afunction of receiving a new browser for making a new service availableand replacing the browser itself with the received new browser.

As such, in order to realize the same transmission function as that of abrowser which essentially carries out the same function for any service,slightly different browsers are required to be implemented.

Accordingly, various wastes arise with an increase in number ofservices. Specifically, the reception device is required to retain aplurality of similar program codes, and therefore storage capacities arewasted by the number of redundant browsers. Also, the reception devicesimultaneously activates similar processes, so that computer resourcescannot be efficiently utilized.

Also, the method for transmitting a browser varies from one service toanother, and the implementation thereof is separately programmed foreach browser for each service. It is troublesome that the user isrequired to previously obtain a browser for a desired service manuallyby manually activating a file transmission protocol such as FTP.

Also, the method for transmitting a browser differs from the method fortransmitting content. Therefore, in the case of subscribing to aplurality of services, transmission of a browser for one service mightprevent transmission of a browser or content for another service.

Also, in the sending device, in order to realize browser transmissionwhich is a function that is essentially consistent for any service,slightly different browser senders are required for the number ofservices. Accordingly, the complexity of the sending device increaseslinearly with an increase of the number of services. This complexityleads to an increase in development cost and the complexity ofmanagement.

Also, there is no association between a plurality of browser senders,therefore there is a possibility that a plurality of browsers might besent out at the same time more than the transmission path can handle,overflowing the transmission path. Since a content sender individuallyexists for each service, content transmission might have a problemsimilar to the problem with the browser transmission.

An object of the present invention is to provide a method and system foruse in non-storage type broadcasting in which a service consisting of aplurality of contents, which are transmitted via digital broadcasting ora computer network, is provided in real-time for viewing, the method andsystem providing a user interface which implements flexible serviceswhile protecting the safety of the services from invalid content.

DISCLOSURE OF THE INVENTION

To achieve the above object, the present invention has the followingaspects.

A first aspect of the present invention is directed to a non-storagetype broadcasting system for providing one or more services composed ofa content in real-time for viewing by a user and providing a userinterface unique to each of the services, the system comprising:

-   -   a transmitter for sending out a control content, which        implements the user interface, as a part or whole of the        content; and    -   a receiver for receiving the sent control content and activating        the received control content to execute the user interface, the        user interface being transmitted/received as a content.

In a second aspect based on the first aspect of the present invention,the control content is a browser for the content.

In a third aspect based on the first aspect of the present invention,the transmitter includes:

-   -   a content sender for sending out a content containing the        control content; and    -   a service attribute information sender for sending out service        attribute information indicating details of the services, and    -   the receiver includes a control content identifier for        identifying the control content from among received contents        based on the received contents and the service attribute        information.

In a fourth aspect based on the third aspect of the present invention,the content sender includes content header addition means for adding, tothe content, a content header which defines details of the content, andthe receiver identifies the control content from among the receivedcontents based on reconnect headers of the received contents.

In a fifth aspect based on the third aspect of the present invention,the transmission means further includes an electronic signature devicefor applying an electronic signature to the control content, the serviceattribute information sender sends out a public key of the electronicsignature in the service attribute information, and

-   -   the receiver further includes a signature authentication device        for authenticating the electronic signature with the public key        contained in received service attribute information, the control        content being identified by authenticating the electronic        signature.

In a sixth aspect based on the fifth aspect of the present invention,the authentication by the electronic signature is performed using a keyindependent of each service.

In a seventh aspect based on the third aspect of the present invention,the content sender further includes a content ID space manager forsending out information which defines a partial space of an ID space ofthe content, and

-   -   the receiver further includes an identifier for identifying the        control content based on whether a content ID falls within the        partial space.

An eighth aspect of the present invention is directed to a controlcontent transmission method for use in a non-storage type broadcastingsystem for providing one or more services composed of a content inreal-time for viewing by a user, the method transmitting a userinterface unique to each of the services, the method comprising:

-   -   a step of sending out a control content, which implements the        user interface, as a part or whole of the content; and    -   a step of receiving the sent control content and activating the        received control content to execute the user interface.

In a ninth aspect based on the eighth aspect of the present invention,the control content is a browser for the content.

In a tenth aspect based on the eighth aspect of the present invention,the step of sending out further includes: a content sending step ofsending out a content containing the control content); and

-   -   a service attribute information sending step of sending out        service attribute information indicating details of the        services, and    -   the reception step includes a control content identification        step of identifying the control content from among received        contents based on the received contents and the service        attribute information.

In an eleventh aspect based on the tenth aspect of the presentinvention, the content sending step includes a content header additionstep of adding, to the content, a content header which defines detailsof the content, and

-   -   the reception step further includes a step of identifying the        control content from among the received contents based on        content headers of the received contents.

In a twelfth aspect based on the tenth aspect of the present invention,the step of sending out further includes an electronic signature step ofapplying an electronic signature to the control content,

-   -   the service attribute information sending step further includes        a service attribute information sending step of sending out a        public key of the electronic signature in the service attribute        information, and    -   the reception step further includes:        -   a signature authentication step of authenticating the            electronic signature with the public key contained in            received service attribute information; and        -   a step of identifying the control content by authenticating            the electronic signature.

In a thirteenth aspect based on the twelfth aspect of the presentinvention, the authentication by the electronic signature is performedusing a key independent of each service.

In a fourteenth aspect based on the tenth aspect of the presentinvention, the content sending step further includes a content ID spacemanagement step of sending out information which defines a partial spaceof an ID space of the content, and

-   -   the reception step further includes a step of identifying the        control content based on whether a content ID falls within the        partial space.

A fifteenth aspect is directed to a reception device for use in anon-storage type broadcasting system for providing one or more servicescomposed of a content in real-time for viewing by a user and providing auser interface unique to each of the services, the reception devicereceiving a control content which implements the user interface, thecontrol content being transmitted as a part or whole of the content andhaving added thereto service attribute information indicating details ofthe services, the reception device comprising:

-   -   a receiver for receiving contents transmitted from a        transmitter;    -   an extractor for demodulating the received contents and        extracting the contents and the service attribute information;        and    -   a control content identifier for identifying the control content        from among the received contents based on the extracted contents        and the service attribute information.

In a sixteenth aspect based on the fifteenth aspect, in the non-storagetype broadcasting system, the content is transmitted after being furtheradded with a content header which defines details of the content,

-   -   the extractor further extracts the content header from the        received contents, and    -   the control content identifier identifies the control content        from among the received contents based on the extracted content        header.

In a seventeenth aspect based on the fifteenth aspect, in thenon-storage type broadcasting system, the control content is signed withan electronic signature, and a public key of the electronic signature issent out in the service attribute information,

-   -   the reception device further includes a signature authentication        device for authenticating the electronic signature with the        public key contained in received service attribute information,        and    -   the control content identifier identifies the control content by        authenticating the electronic signature.

In an eighteenth aspect based on the seventeenth aspect, theauthentication by the electronic signature is performed using a keyindependent of each service.

In a nineteenth aspect based on the fifteenth aspect, in the non-storagetype broadcasting system, the content is added with information whichdefines a partial space of an ID space of the content, and

-   -   the identifier further identifies the control content based on        whether a content ID falls within the partial space.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram showing a structure of a non-storage typebroadcasting system according to a first embodiment of the presentinvention.

FIG. 2 is a diagram for explaining service attribute information storedin a service attribute storage shown in FIG. 1.

FIG. 3 is a schematic diagram showing examples of content bodies storedin a content storage shown in FIG. 1.

FIG. 4 is a table for explaining service attribute information in thenon-storage type broadcasting system shown in FIG. 1.

FIG. 5 is a diagram for explaining a service content in the non-storagetype broadcasting system shown in FIG. 1.

FIG. 6 is a diagram for explaining a browser content in the non-storagetype broadcasting system shown in FIG. 1.

FIG. 7 is a schematic diagram showing examples of contents stored in astorage shown in FIG. 1.

FIG. 8 is a schematic diagram showing information stored in a memoryshown in FIG. 1.

FIG. 9 is a flowchart showing an operation of executing a browsercontent by a non-storage type reception device shown in FIG. 1.

FIG. 10 is a flowchart showing an operation of updating a browsercontent by the non-storage type reception device shown in FIG. 1.

FIG. 11 is a block diagram showing a structure of a non-storage typebroadcasting system according to a second embodiment of the presentinvention.

FIG. 12 is a table for explaining service attribute information in thenon-storage type broadcasting system shown in FIG. 11.

FIG. 13 is a diagram for explaining a browser content in the non-storagetype broadcasting system shown in FIG. 11.

FIG. 14 is a flowchart showing an operation of updating a browsercontent by a non-storage type reception device shown in FIG. 11.

FIG. 15 is a block diagram showing a structure of a non-storage typebroadcasting system according to a third embodiment of the presentinvention.

FIG. 16 is a table for explaining service attribute information in thenon-storage type broadcasting system shown in FIG. 15.

FIG. 17 is a diagram for explaining a browser content in the non-storagetype broadcasting system shown in FIG. 15.

FIG. 18 is a flowchart showing an operation of updating a browsercontent by a non-storage type reception device shown in FIG. 15.

FIG. 19 is a block diagram showing a structure of a non-storage typebroadcasting system according to a fourth embodiment of the presentinvention.

FIG. 20 is a table for explaining service attribute information in thenon-storage type broadcasting system shown in FIG. 19.

FIG. 21 is a table for explaining a content ID in the non-storage typebroadcasting system shown in FIG. 19.

FIG. 22 is a diagram for explaining a browser content in the non-storagetype broadcasting system shown in FIG. 19.

FIG. 23 is a flowchart showing an operation of updating a browsercontent by a non-storage type reception device shown in FIG. 19.

FIG. 24 is a block diagram showing a structure of a conventionalnon-storage type broadcasting system.

FIG. 25 is a schematic diagram showing examples of contents stored incontent and browser storages shown in FIG. 24.

FIG. 26 is a schematic diagram showing an example of a content andbrowsers stored in a storage shown in FIG. 24.

FIG. 27 is a schematic diagram showing information stored in a memoryshown in FIG. 24.

FIG. 28 is a table for explaining service attribute information in thenon-storage type broadcasting system shown in FIG. 24.

FIG. 29 is a flowchart showing an operation of executing a browser by areception device shown in FIG. 24.

FIG. 30 is a flowchart showing an operation of updating a browser by thereception device shown in FIG. 24.

BEST MODE FOR CARRYING OUT THE INVENTION First Embodiment

Referring to FIGS. 1, 2, 3, 4, 5, 6, 7, 8, 9, and 10, a non-storage typebroadcasting system according to a first embodiment of the presentinvention is described.

As shown in FIG. 1, a non-storage type broadcasting system 100 accordingto the first embodiment includes a transmission device 110, atransmission path 120, and a non-storage type reception device 130. Aswill be described later, the non-storage type reception device 130stores a browser but does not store content itself, and therefore it isreferred to as the non-storage type.

The transmission device 110 includes a service attribute storage 111, acontent header adder 112, content storages 113, a content sender 114, amultiplexer 115, and a sender 116. A plurality of content storages 113are provided, and they are distinguished from each other by assigning asuffix (a lower-case alphabetic character) to their respective symbols.In the following descriptions, if a plurality of elements of the sametype are present, they are distinguished from each other similarly byassigning a suffix to their respective symbols. Note that if there is noneed to individually distinguish them, they are collectively referred toas the content storages 113, for example.

As described above, if there are a plurality of elements of the sametype, they are distinguished herein similarly by adding a suffix totheir respective symbols. Further, if there is no need to individuallydistinguish them, they are referred to by their respective generic nameswithout assigning a suffix to their symbols

Each of the content storages 113 has stored therein a content body Dcwhich is substantive data of a service. Further, the content storages113 sequentially supply the content bodies Dc to the content sender 114.

The content sender 114 sends the supplied content bodies Dc to thecontent header adder 112.

The content header adder 112 adds to the supplied content bodies Dc, acontent header Hc consisting of management information of the contentbodies Dc including header information, thereby generating content C.The generated content C is supplied to the multiplexer 115.

The multiplexer 115 multiplexes service attribute information Ispsupplied from the service attribute storage 111 with content C outputtedfrom the content header adder 112, and supplies it to the sender 116.

The sender 116 modulates the service attribute information Isp modulatedwith the content C into a digital bit stream in the form adapted to thetransmission path, and then transmits it to the transmission path 120.The sender 116 may be a modem if the transmission path is a wiredcommunication line, or may be a parabolic antenna for sending if thetransmission path is a broadcasting communications satellite and outerspace.

The transmission path 120 is a means for transmitting to the non-storagetype reception device 130 information, such as the content C or thebrowser B, which has been transmitted from the transmission device 110.For example, the transmission path can be composed of an optical fiber,a cable of any type, a broadcasting communications satellite andouterspace, or a package medium such as a DVD and a distribution channelthereof.

The non-storage type reception device 130 includes a receiver 131, ademodulator/separator 132, a storage 133, a renderer 134, a presenter135, an input device 136, a CPU 137, and a memory 138. Note that thestorage 133, the renderer 134, the input device 136, the CPU 137, andthe memory 138 are interrelated with each other via a data buss.

The receiver 131 receives information, such as the content C or thebrowser B, which has been transmitted to the transmission path 120, andoutputs a digital stream. The receiver 131 can be composed of a mobilecommunication module, such as a communication modem, a cable modem, orBluetooth, and an antenna and tuner module for an ordinary digitalbroadcast receiver.

The demodulator/separator 132 demodulates the digital bit streamoutputted by the receiver 131, and separates multiplexed informationinto pieces of information. The demodulator/separator 132 performs aprocess opposite to that of the multiplexer 115 of the transmissiondevice 110. The outputs of the demodulator/separator 132 are supplied tothe storage 133 and the renderer 134, and can be read by the CPU 137.

The storage 133 is, for example, a randomly accessible storage mediumsuch as a hard disk, and information thereon can be read and modified bythe CPU 137. Among service content C (Sm,O) and browser content C(Sm,Bflg) outputted from the demodulator/separator 132, the storage 133stores only the browser content C (Sm, Bflg). This is because thenon-storage type reception device 130 displays, in real-time, theservice content C (Sm,O) transmitted from the transmission device 110and thus are not required to store the service content C (Sm,O), whilethe browser content C(Sm, Bflg) containing the browser B for presentingthe distributed service content C (Sm,O) has to always be prepared.

The service content C (Sm,O) corresponds to an essence of a serviceprovided by the non-storage type broadcasting system 100, e.g., aprogram or data which the user enjoys viewing. The browser content C(Sm,Bflg) implements a user interface for allowing the user to actuallyenjoy a provided service with the non-storage type reception device 130.The browser content C (Sm,Bflg) is a control code executable under aprogram code execution environment provided by the non-storage typereception device 130, and is intended to process the service content C(Sm,O).

In response to a request from the CPU 137, the renderer 134 renders OSD(on-screen display) and the service content C (Sm,O), which is inputtedfrom the demodulator/separator 132, into graphics that are to bedisplayed on the screen.

The presenter 135 presents outputs of the renderer 134 in forms that areviewable/audible to the user. The presenter may be a CRT display, forexample.

The input device 136 is used by the user to provide an instruction foroperation to the non-storage type reception device 130. The input device136 can be composed of a combination of a remote control and a lightreception portion of the remote control, a keyboard, a mouse, or thelike.

The CPU 137 is a central processing unit which is interconnected to eachelement of the non-storage type reception device 130, and operable toexecute a computer program stored in the memory 138 to control theentire non-storage type reception device 130.

The memory 138 is composed of a RAM/ROM which is arewritable/non-rewritable semiconductor memory, and used as a region forstoring data of processing by the CPU 137 or a computer program or datathat is to be executed by the CPU 137.

Referring to FIGS. 2, 3, 4, and 5, data stored in each element of theabove-described non-storage type broadcasting system 100 is described.

As shown in FIG. 2, the service attribute storage 111 has stored thereinservice attribute information Isp indicating an attribute of eachservice provided by the non-storage type broadcasting system 100.

As shown in FIG. 3, the content storage 113 has stored therein a contentbody Dc which is an essence of the content C which is data constitutinga corresponding service. The content storage 113 individually exists foreach service. Specifically, there are provided three individual contentstorages 113 a, 113 b, and 113 c corresponding to three differentservices.

The content storage 113 a corresponding to service S1 has stored thereintwo content bodies Dc(S1,1) and Dc(S1,2) and one browser content bodyDc(S1,Bflg). Note that an arbitrary content body Dc is represented as acontent body Dc(Sm,O) by assigning suffix m (an arbitrary naturalnumber) to symbol S, which denotes a service, to identify an individualservice, and assigning parameter O (an arbitrary natural number), whichindicates the position in a sequence of a plurality of contents Cconstituting service Sm.

The browser content body Dc(S1,Bflg) is obtained by generating browserB(S1), which is used for service Si, in the same format as that of thecontent body Dc, and can be represented by the body Dc(Sm,Bflg) in amanner similar to the service content body Dc(Sm,O).

The browser content body Dc (Sm,Bflg) is different in details from theservice content body Dc(Sm,O). Specifically, it contains, instead of O,parameter Bflg which indicates service attribute information Isp. Notethat the service attribute information Isp will be described in detaillater with reference to FIG. 4.

However, the browser content body Dc(Sm,Bflg) is in the same data formatas that of the service content body Dc(Sm,O), therefore the contentstorage 113 cannot distinguish them and handles both of them as thecontent body Dc. In this context, both the browser content bodyDc(Sm,Bflg) and the service content body Dc(Sm,O) are collectivelyreferred to as content body Dc. For simplification, the service contentbody Dc(Sm,O) and the browser content body Dc(Sm,Bflg) are referred toas service content body DcS and browser content body DcB, respectively,if need arises. Further, the browser content C(Sm,Bflg) containing thebrowser content body Dc(Sm,Bflg) is simply referred to as browsercontent Cb, and the service content C(Sm,O) containing the servicecontent body Dc(Sm,O) is simply referred to as service content Cs.

Next, referring to FIGS. 4, 5 and 6, service content Cs and browsercontent Cb, which are outputted from the content header adder 112, aredescribed in detail. FIG. 4 illustrates by way of example serviceattribute information Isp stored in the service attribute storage 111.The service attribute information Isp is information related to allservices (S1, S2, . . . , Sm) provided by the non-storage typebroadcasting system 100. In the table, each row corresponds to aservice, and contains a service ID and a service name.

For example, the top row shows a service having the service ID “S1” andthe service name “TODAY'S NEWS”. Similarly, the second row shows aservice having the service ID “S2” and the service name “RECOMMENDATIONINFORMATION”, and the third row shows a service having the service ID“S3” and the service name “NEW CAR GUIDE”. The service ID is representedby a unique value in the service attribute information Isp, and can beused for identifying the service.

FIG. 5 schematically shows a data structure of the service content Cs,and FIG. 6 schematically shows a data structure of the browser contentCb. The content C is composed of a content body Dc, which is essentialdata of the content C it self, and a content header Hc, which ismetadata associated with the content body Dc.

In FIG. 5, a service content body DcS of content C(S1,1), which is theservice content Cs, is associated with a content header HcS. In FIG. 6,a browser content body DcBn of C(S1,Bflg), which is the browser contentCb, is associated with a content header HcB.

The content headers Hc (i.e., HcS and HcB) are represented in the formof a table in which a row consists of a set of an item and a value. Thecontent header HcS of the service content Cs (i.e., C(S1,1)) includesfour rows, i.e., SERVICE ID, CONTENT ID, CONTENT VERSION, and CONTENTNAME.

The service ID corresponds to a service ID in the service attributeinformation Isp illustrated in FIG. 4, and identifies to which service Sthe content C corresponds. In present example, the service ID is S1, andtherefore it is indicated that the content C is the “TODAY'S NEWS”service shown in FIG. 4.

The content ID is used for identifying the content C itself.Accordingly, the content ID is managed, for example, so as to avoidoverlaps on the sending side, and has a unique value at least in thenon-storage type broadcasting system 100.

The content version indicates whether the content C is old or new. Thecontent version has an individual value for each content ID. If it isdesired to replace a current content Cc, which is currently stored inthe storage 133 that is to be described in detail later with referenceto FIG. 7, with a new content Cn to which it is desired to be updated, acontent version having a value greater than that of the current contentCc is assigned to the new content Cn when the content C is sent out.

The content name is an item to be read as a character string when theuser selects the content. In the present example, it is indicated thatthe content body Dc is the “WEATHER FORECAST”.

The above-described service ID, content ID, content version, and contentname are commonly contained in the service content header HcS and thebrowser content header HcB.

However, as shown in FIG. 6, the browser content header HcB of thebrowser content Cb further contains a browser content flag row.

The browser content flag Bflg is an item for indicating that the contentC is the browser content Cb, and corresponds to the above-describedparameter Bflg. The browser content flag of the browser content headerHcB is indicated as “True”, therefore it is indicated that the contentbody Dc is the browser content body DcB.

In the browser content Cb illustrated in FIG. 6, the service ID is S1and the content ID is 101. Therefore, it is indicated that the browsercontent Cb for the service “TODAY'S NEWS” contains the content body Dchaving the content ID “101”. Thus, three of the service ID, the contentID, and the browser content flag are information at least required fordefining that the content C is the browser content Cb.

Hereinbelow, processes which the service attribute storage 111, thecontent header adder 112, the content storage 113, and the contentsender 114 perform based on the above-described data structure of thecontent C are described.

The content sender 114 sends to the content header adder 112 contentbodies Dc sequentially supplied by the content storage 113. The contentheader adder 112 assigns a content header Hc (HcS, HcB) to a contentbody Dc (i.e., DcS, DcB) to generate content C (i.e., Cs, Cb), andsupplies it to the multiplexer 115.

The following description is given by referring to FIGS. 7 and 8 withrespect to what type of data is stored in each element of thenon-storage type reception device 130 when content C (service contentCs, browser content Cb) is transmitted from the transmission device 110via the transmission path 120.

A digital bit stream transmitted from the transmission device 110 viathe transmission path 120 and containing the content C and the serviceattribute information Isp is first received by the receiver 131 of thenon-storage type reception device 130, and then supplied to thedemodulator/separator 132.

The demodulator/separator 132 demodulates the digital bit stream, andseparates and reproduces the content C and the service attributeinformation Isp which are contained in the demodulated digital bitstream. Further, the demodulator/separator 132 extracts a content headerHc from the reproduced content C, and outputs it to a bus together withthe service attribute information Isp.

The reproduced content C is temporarily retained in thedemodulator/separator 132. Note that where it is necessary todistinguish the reproduced content C from content C having beenpreviously stored in the storage 133, the content C retained in thedemodulator/separator 132 is referred to as “demodulated content Cn” andthe content C stored in the storage 133 is referred to as “storedcontent Ca”.

The content C reproduced by the demodulator/separator 132 is supplied ata predetermined time and stored into the storage 133. As shown in FIG.7, among contents C (i.e., Cs, Cb) of services outputted from thecontent header adder 112 to the multiplexer 115, only the browsercontent Cb is stored in the storage 133. Specifically, as described withreference to FIG. 7, only the browser content Cb is stored as the storedcontent Ca stored in the storage 133.

That is, among contents C(S1,Bflg), C(S1,1), C(S1,2), C(S2, Bflg),C(S3,Bflg), C(S3,1), C(S3,2), and C(S3,3) which respectively correspondto a total number of eight content bodies Dc(S1,Bflg), Dc(S1,1),Dc(S1,2), Dc(S2, Bflg), Dc(S3,Bflg), Dc(S3,1), Dc(S3,2), and Dc(S3,3),which are stored in the content storages 113 a, 113 b, and 113 c shownin FIG. 3, the contents C(S1,Bflg), C(S2,Bflg), and C(S3,Bflg) arestored in the storage 133.

Further, the storage 133 is controlled by the CPU 137 so as to outputthe browser content body Dc(S,Bflg), which is contained in the storedbrowser content Cb, to a bus or the renderer 134.

The renderer 134 generates, based on the supplied information, a videosignal for rendering an image on the presenter 135.

As shown in FIG. 8, the memory 138 has stored therein the serviceattribute information Isp, a browser content execution interpreter 271,and an execution form 2651 which is a native code of the CPU 137. Thebrowser content execution interpreter 271 is used for executing contentas a computer high-level language program.

Next, referring to a flowchart shown in FIG. 9, an operation ofactivating the browser content Cb contained in the content C receivedbythe non-storage type reception device 130 is described.

At step S501, a list of service names of services described by theservice attribute information Isp outputted from thedemodulator/separator 132 is displayed on the screen of the presenter135.

At step S502, a service selected from the list of service namesdisplayed at step S501 is detected based on the user's operation of theinput device 136. Specifically, the service selected by the user isidentified based on the user's operation of the input device 136 and thelist of service names.

At step S503, a service ID corresponding to the service identified atstep S502 is obtained from the service attribute information Isp.

At step S504, all contents C stored in the storage 133 are searchedthrough in order to select a content Cb having the service ID obtainedat step S503 and a content header HcB with a browser content flag Bflgindicated as “True”.

At step S505, the browser content Cb selected at step S504 is executedby the browser content execution interpreter 271.

In this manner, SINCE the browser content flag Bflg is contained in thecontent header HcB of the browser content Cb, the browser content Cb canbe distinguished from other ordinary service contents Cs. Also, bydesignating an individual service S, a browser content Cb correspondingthereto (i.e., C(Sm,Bflg)) can be activated as a browser.

Next, referring to a flowchart shown in FIG. 10, an operation performedby the non-storage type reception device 130 for updating the browsercontent Cb is described.

At step S601, the demodulator/separator 132 reproduces the content Cn(i.e., Cb, Cs), the service attribute information Isp, and the contentheader Hc (i.e., HcB, HcS).

At step S608, it is determined whether the browser content flag Bflg ofthe newly separated content Cn is “True”. If it is “False”, theprocedure returns to the above step S601. Note that if there is nobrowser content flag Bflg, i.e., in the case of the service content Cs,it is determined at this step as being false. If the browser contentflag Bflg is true, i.e., in the case where the new content Cn is thebrowser content Cb, the procedure proceeds to the next step S602.

At step S602, the content header Hc separated at step S601 is outputtedto a bus. Specifically, only the browser content header HcB of thebrowser content Cb is outputted.

At step S603, the storage 133 is searched through to select a newcontent Cc (browser content Cb) corresponding to the separated contentheader Hc. Specifically, the current content Cc (browser content Cb)having the same service ID as that written in the separated contentheader Hc is selected from among all browser contents Cb stored in thestorage 133.

At step S604, if it is determined that the storage 133 includes nobrowser content Cb having the same content ID, the procedure proceeds tothe next step S605.

At step S605, a new browser content Cn (Cb) to which none in the storage133 corresponds is stored anew as the current browser content Cc (Cb).Then, the procedure returns to the above step S601.

On the other hand, at step S604, if it is determined based on a searchresult of step S602 that the storage 133 contains a browser content Cb(current content Cc) having the same content ID, the procedure proceedsto step S606.

At step S606, whether the new browser content Cn (Cb) separated at stepS601 is newer than the current browser content Cn (Cb) stored in thestorage 133 is determined based on a content version contained in thebrowser content header HcB outputted at step S602. If it is determinedas being new, the procedure proceeds to the next step S607.

At step S607, the current browser content Cn (Cb) stored in the storage133 is updated by the new browser content Cn (Cb) retained in thedemodulator/separator 132. Note that at this point, the new browsercontent Cn (Cb) becomes a current browser content Cc. Then, theprocedure returns to step S601.

On the other hand, at step S606, if it is determined that the newlydemodulated browser content Cn (Cb) is not newer than the current newbrowser content Cc (Cb) stored in the storage 133, the above step S607of updating the current browser content Cn (Cb) is skipped, and theprocedure returns to step S601.

As described above, in the non-storage type broadcasting system 100, thetransmission device 110 sends the browser content Cb, which provides auser interface to each service Sm, as part or whole of content Cconstituting the service Sm. Then, the non-storage type reception device130 receives the sent content C, and activates the browser content Cbcontained in the received content C, thereby executing the userinterface. Note that the procedure shown in FIG. 10 may be executed aspart of step S504 of the flowchart shown in FIG. 9, or may be executedonly when it is necessary to update the browser content Cb.

Then, the browser content Cb is automatically updated or retained at atime point when the one of a version newer than that stored in thenon-storage type reception device 130 is distributed, or when the one ofany version other than those retained in the non-storage type receptiondevice 130 is distributed. Specifically, the process of updating thecontent C is carried out only when the content C is the browser contentCb. This mechanism is not a function for each specific service, but is afunction unique to the entire non-storage type reception device 130 andcommon to all services. Accordingly, by merely realizing the function ofupdating the browser content Cb, it is possible not only to processservice contents Cs for all the services in real-time but also to updateand store the browser, i.e., the browser content Cb.

In other words, in the present embodiment, by transmitting the browsercontent Cb, which is a user interface for each service, as part ofcontent, it is made possible to eliminate of the need of preparing aspecial mechanism for transmitting a user interface for each service andto update the user interface as if content is updated.

Second Embodiment

Hereinbelow, referring to FIGS. 11, 12, 13, and 14, a non-storage typebroadcasting system according to a second embodiment of the presentinvention is described. As shown in FIG. 11, similar to the non-storagetype broadcasting system 100 as shown in FIG. 1, a non-storage typebroadcasting system 700 according to the present embodiment includes atransmission device 710, a transmission path 120, and a non-storage typereception device 730.

The transmission device 710 is such that the transmission device 110 ofthe non-storage type broadcasting system 100 additionally includes anelectronic signature device 711. The non-storage type reception device730 is such that the non-storage type reception device 130 additionallyincludes a KP extractor 740, an Sg extractor 741, and a decoder 721.Hereinbelow, features specific to the non-storage type broadcastingsystem 700 are mainly described, and the descriptions of features commonto the non-storage type broadcasting system 100 are omitted.

The digital signature device 711 manages electronic signature keys, andapplies an electronic signature (digital signature) to browser contentCb. As an electronic signature, a technique for public key cryptographyis used. In this technique, a set of a secret key and a public key aregenerated for a distributor of information, and while only the publickey is distributed to users of the information, the secret key is keptin secret. The distributor uses the secret key to apply an electronicsignature to information that is desired to be distributed (theinformation to which the electronic signature has been applied isprovided in the form of a combination of original information and theelectronic signature). The information to which the electronic signatureis applied and which is received by the user and the distributor'spublic key are used to make it possible to authenticate that thedistributor having the secret key has applied the electronic signatureto that information.

The electronic signature device 711 has a combination of a secret keyand a public key for each service. The electronic signature device 711uses the secret key of the service to apply an electronic signature tothe browser content Cb of the service. Specifically, the electronicsignature device 711 is connected to the content storage 113 andoutputs, in accordance with services of the content bodies Dcrespectively supplied from the content storages 113 a, 113 b, and 113 c,public keys KP different among the services to the service attributestorage 111.

Specifically, as shown in FIG. 13, by adding the item of ELECTRONICSIGNATURE to the content header HcB of the browser content Cb, theelectronic signature is contained in the browser content Cb.Accordingly, unlike the browser content Cb, browser content Cbc(S1,Bsgn) has a content header with an electronic signature row. A valuecolumn of the electronic signature row contains information (electronicsignature) about a result of applying an electronic signature to acorresponding content body Dc with a secret key of service S1 to whichthe content belongs.

The content header HcB assigned with the electronic signature isspecified as content header HcBc. Further, in order to distinguish abrowser content with an electronic signature item from other browsercontents Cb, that browser content is referred to as browser content Cbc,and represented by C(Sm,Bsgn).

The service attribute storage 111 generates service attributeinformation Ispc including a public key KP, and outputs it to themultiplexer 115. FIG. 12 shows the structure of the generated serviceattribute information Ispc. The service attribute information Ispc has acolumn for storing public keys KP. The public keys stored correspond tothree services S1, S2, and S3.

Further, the electronic signature device 711 generates electronicsignature Sg, and outputs it to the content header adder 112. Thecontent header adder 112 generates a browser content Cbc with asignature based on the content body Dc supplied from the content sender114 and the electronic signature Sg supplied from the electronicsignature device 711, and outputs, to the multiplexer 115, content Cconsisting of the browser content Cbc with a signature and a servicecontent Cs.

The non-storage type reception device 730 reproduces the content C (Csand Cbc), content headers Hc (HcS,HcBc), and the service attributeinformation Ispc from a digital bit stream received by thedemodulator/separator 132. The content C (Cs and Cbc) is retained in thedemodulator/separator 132, the content headers Hc (HcS and HcBc) areoutputted to a bus and the Sg extractor 741, and the service attributeinformation Ispc is outputted to the KP extractor 740.

The Sg extractor 741 extracts the electronic signature Sg from thecontent header Hc of the browser content C (Sm, Bflg) among the suppliedcontent headers Hc, and outputs it to the bus.

The KP extractor 740 extracts the public key KP from the serviceattribute information Ispc, and outputs it to the bus.

The decoder 721 authenticates an electronic signature in the contentheader HcBc based on the public key KP supplied via the bus.

As described above, the non-storage type reception device 730 is able toauthenticate the correctness of the received browser content Cbc basedon the electronic signature Sg of the browser content Cbc and the publickey KP in the service attribute information Ispc. Thus, a contentcreator of each service is able to ensure that the browser content Cbcis encrypted with a secret key unique to the service.

Next, an operation of the non-storage type reception device 730according to the second embodiment is described. The operation of thenon-storage type reception device 730 for activating the browser contentCb contained in the received content C is basically the same as that ofthe non-storage type reception device 130 according to the firstembodiment described with reference to the flowchart shown in FIG. 9,except that the service attribute information Isp is changed to Ispc andthe target content C is changed to the browser content Cbc. Accordingly,the description of the operation is omitted.

Now, referring to a flowchart shown in FIG. 14, an operation performedby the non-storage type reception device 730 for updating the browsercontent Cb is described. The operation performed by the non-storage typereception device 730 for updating the browser content Cb is similar tothe operation performed by the non-storage type reception device 130 forupdating the browser content Cb as described with reference to FIG. 10.Specifically, in the flowchart shown in FIG. 14, steps S1001, S1002,S1003, and S1004 are additionally provided between steps S602 and S603in the flowchart shown in FIG. 10.

That is, as described above, after the processes of steps S601 and S602,the browser content Cb is targeted for processing, and the procedureproceeds to the additionally provided step S1001.

At step S1001, an obtained browser content Cbc is referenced for the rowof the electronic signature stored in the content header HcB. If thereis any electronic signature item, the procedure proceeds to step S1002.

At step S1002, it is authenticated whether the electronic signature Sgof the browser content Cbc has been applied with a secret keycorresponding to a public key KP of a corresponding service. The publickey KP used therefor is the one obtained by selecting the row of thatcorresponding service from the service attribute information Ispc. Theprocedure proceeds to the next step S1003.

If it is determined at step S1003 based on a result of theauthentication at step S1002 that the electronic signature Sg is notcorrect, the procedure proceeds to step S1004.

At step S1004, a warning that the browser content Cbc with a signatureis invalid is displayed, and the procedure is terminated. Accordingly,in any cases where it is determined that there is any abnormality in theelectronic signature (No at step S1001 or S1003), the warning is issuedat this step, and then the procedure proceeds to the above-describedstep S603.

In contrast, if it is determined at step S1003 that the electronicsignature is correct, the above-described step S1004 is skipped, and theprocedure proceeds to steps S604, S605, S606, and S607, as in the caseof the first embodiment.

As described above, in the non-storage type broadcasting system 700according to the present embodiment, as in the non-storage typebroadcasting system 100, a sent content C is received, and a userinterface is executed by activating a browser content Cb contained inthe received content C. However, the non-storage type broadcastingsystem 700 employs an electronic signature technique so that only theone in possession of the secret key of a target service is able to senda browser content Cb executable in the non-storage type reception device730.

Thus, even if the one who is out of possession of the secret key for thetarget service attempts to store whatever content into the contentstorage, it is possible to prohibit intentionally transmitting anerroneous browser content Cb to execute it in the non-storage typereception device 730. Also, it is possible to prohibit a browser contentCb to which an electronic signature is applied with a secret key of aservice other than the target service from being executed as the browsercontent Cb of the target service.

Note that although the electronic signature is applied only to thecontent body for the reason of simplifying the mechanism, the contentheader may be contained in the content body such that the electronicsignature is applied thereto.

Note that a simple electronic signature method which does not use publickey encryption may be used. For example, a secret key may be generatedfor each service, and the secret key may be stored in the receptiondevice by any method. Information which provides an indication of thebrowser content Cb may be encrypted with the secret key for eachservice, and the information may be decrypted on the reception deviceside to determine that it is the browser content Cb.

As described above, in the present embodiment, it is possible to ensurethe reliability of content C distributed in the non-storage typebroadcasting system 700 since the system includes: the electronicsignature device 711, which applies an electronic signature to thebrowser content Cbc, which is content for providing a user interface foreach service; the content storage 113 which sends the content body Dccontaining browser content body DCbc; the service attribute storage 111which sends the public key KP of the electronic signature Sg as theservice attribute information Ispc common to all the services; and thenon-storage type reception device 730 which authenticates the electronicsignature Sg to determines that the content C is the browser contentCbc.

That is, in the present embodiment, the electronic signature is used fora mechanism of designating the browser content Cb from among a pluralityof contents C belonging to one service, and a key used for theelectronic signature is prepared for each service provider, so that noone but the provider can designate the browser content Cb for thatservice. As a result, it is possible to prevent the browser content Cbfrom being incorrectly designated by the one other than the serviceprovider who has malicious intent.

Third Embodiment

Next, referring to FIGS. 15, 16, 17, and 18, a non-storage typebroadcasting system according to a third embodiment of the presentinvention is described. As shown in FIG. 15, similar to the non-storagetype broadcasting system 100 shown in FIG. 1, a non-storage typebroadcasting system 1000 according to the present embodiment includes atransmission device 1010, a transmission path 120, and a non-storagetype reception device 130. The transmission device 1010 is such that thecontent header adder 112 of the transmission device 110 in thenon-storage type broadcasting system 100 is replaced with a contentheader adder 112 i. Hereinbelow, features specific to the non-storagetype broadcasting system 1000 are mainly described, and the descriptionsof features common to the non-storage type broadcasting system 100 areomitted.

In addition to the functions of the content header adder 112, thecontent header adder 112 i has the following functions. Specifically,for a plurality of content bodies Dc stored in the content storages 113a, 113 b, and 113 c, browser contents Cbi are designated, and contentIDs and content versions of the designated contents (browser contentsCbi) are extracted as browser identification information Bid. Then, thecontent header adder 112 i outputs the extracted browser identificationinformation Bid to the service attribute storage 111.

As shown in FIG. 16, the service attribute storage 111 writes thecontent IDs and content versions of the browser contents Cb into theservice attribute information Isp based on the browser identificationinformation Bid. Specifically, the service attribute information Ispihas a browser content designation information column consisting of acolumn indicating the content IDs and a column indicating contentversions.

The browser content designation information is designated for eachservice, thereby making it possible to identify a browser contentCb(Cbi) among contents. In this manner, the service attributeinformation Isp in which the content ID and content version of thebrowser content Cbi are written is identified as the service attributeinformation Ispi.

The designation of the browser content Cbi is not performed based on thebrowser content flag of the content header HcBi, but it is performed bythe content header adder 112 i selecting the content.

FIG. 17 shows an exemplary content header HcBi. Since the designation ofthe browser content Cbi is not performed based on the browser contentflag Bflg, the content header Hcbi does not have a row for the browsercontent flag Bflg. On the content header, it is not possible todistinguish between service content Cs and browser content Cb. In thepresent embodiment, although it seems that the browser content Cb isrecognizable based on the row of the content name because a human beingrecognizes the meaning of a character string by reading it, it is notrecognizable on the level of the transmission device 1010 and thenon-storage type reception device 130.

Next, an operation of the non-storage type reception device 130according to the present embodiment is described. The operation of thenon-storage type reception device 730 for activating the browser contentCb contained in a received content C is basically the same as that ofthe non-storage type reception device 130 according to the firstembodiment described with reference to the flowchart shown in FIG. 9,except that the service attribute information Isp is changed to Ispc andthe target content C is changed to the browser content Cbc. Accordingly,the description of the operation is omitted.

As described above, in the non-storage type broadcasting system 1000,the non-storage type reception device 130 is configured in the samemanner as that of the non-storage type broadcasting system 100, butthere are slight differences in operation because program codes and datathat are to be stored are different. Now, referring to a flowchart shownin FIG. 18, an operation of updating browser content Cb by thenon-storage type reception device 130 according to the presentembodiment is described. As shown in FIG. 18, in the operation ofupdating the browser content Cb in accordance with the presentembodiment, step S608 of the flowchart shown in FIG. 10 is replaced bysteps S1401 and S1402.

Specifically, at step S1401, for a service selected by the user (S502,S503), the service attribute information Ispi is referenced to retrievebrowser content designation information based on the content C (i.e.,Cn) demodulated and the content header Hc separated at step S601.

At step S1402, the storage 133 is searched through to select content C(browser content Cbi) in possession of the content ID and contentversion of the browser content designation information retrieved at stepS1401. Then, the selected content C is determined as the browser contentCbi, and thereafter the procedure proceeds to the above-described stepS604. On the other hand, as a result of the search, if no correspondingcontent C (browser content Cbi) is selected, the procedure proceeds tostep S601.

The designation of the browser content Cbi is performed by the contentheader adder 112 i. Accordingly, by appropriately managing the contentheader adder 112 i, it is possible to prevent the browser content Cbifrom being repeatedly designated or to prevent a content C for adifferent service from being erroneously designated as the browsercontent Cbi.

As described above, in the present embodiment, it is possible to realizethe non-storage type broadcasting system 100 which ensures that thebrowser content Cbi is distinguished from the service content Cs byproviding the system with the content sender 114 for sending a contentbody constituting each service; the service attribute storage 111 whichsends the service attribute information Ispi containing, as browsercontent designation information common to all services, the browseridentification information Bid for designating the browser content bodyDCb from a plurality of content bodies; and the non-storage typereception device 130 which determines whether content C is the browsercontent Cbi, based on the browser content designation information.

Specifically, in the present embodiment, the browser content Cbi isdesignated based on control content designation information common to aplurality of services, and the browser content designation informationis provided independently of content and content headers. Thus, it ispossible to prevent the browser content Cb from being incorrectlydesignated for a different service regardless of contents of the contentstorage. For example, if the operation is such that the browser contentCb designation information is managed under a contract broadcaster,rather than under each service provider, it is possible to prevent thebrowser content Cb from being incorrectly designated by a plurality ofservice providers.

Fourth Embodiment

Next, referring to FIGS. 19, 20, 21, 22, and 23, a non-storage typebroadcasting system according to a fourth embodiment of the presentinvention is described. As shown in FIG. 19, similar to the non-storagetype broadcasting system 100 shown in FIG. 1, a non-storage typebroadcasting system 1500 according to the present embodiment includes atransmission device 1510, a transmission path 120, and a non-storagetype reception device 130. The transmission device 1510 is such that thetransmission device 110 of the non-storage type broadcasting system 100is additionally provided with a content ID space manager 1501.

Hereinbelow, features specific to the non-storage type broadcastingsystem 1500 are mainly described, and the descriptions of featurescommon to the non-storage type broadcasting system 100 are omitted.

For each service, the content ID space manager 1501 manages the range(space) of values for the content ID of content belonging to theservice, thereby designating browser content Cbs.

For example, the content ID space is defined by the conditions that thecontent is a content having the service ID “S1” if the content ID isbetween 100 and 199; the content is a content having the service ID “S2”if the content ID is between 200 and 299; the content is a contenthaving the service ID “S3” if the content ID is between 300 and 399, andthe content is browser content Cb (Cbc) if the content ID is between 0and 99.

The content ID space manager 1501 generates a content space definitionCSD and outputs it to the content header adder 112. Based on the contentspace definition CSD, the content header adder 112 rewrites the valuefor the item of the content ID, which is stored in the content header Hc(HcBs) of the content body Dc (DcBs) supplied from each of the contentstorages 113 a, 113 b, and 113 c via the content sender 114, into thevalue of a content ID adapted to the defined content ID space.

FIG. 21 shows an exemplary content space definition CSD. The contentspace definition CSD contains information for defining content spaces,as well as a column indicating ranges of content IDs. In this example,for each service, content is generated in which the content ID is freelyset within the range from 0 to 99, and the content is stored in eachcontent storage. Regarding service S1, the browser content Cbs generatedfrom content body Dc supplied from the content storage 113 a isoutputted if it can be confirmed that the content ID thereof is between0 and 99. In this case, if the content ID is not between 0 and 99, thebrowser content Cbs is considered as being an invalid content and thusremoved.

For the service content Cs, which is content of the service S1, thecontent ID is converted into a value between 100 and 199 by adding 100thereto. After the conversion, whether it is between 100 and 199 isconfirmed. If so, the service content is outputted, and if it is notbetween 100 and 199, the service content is considered as being aninvalid content and thus removed.

Note that during the conversion, similar conversion is performed oncontent IDs used for referencing other contents embedded in the content.

FIG. 22 shows an exemplary structure of the browser content Cbs afterthe rewriting by the content ID space manager 1501. In the contentheader HcBs of the browser content Cbs, the content ID is 001 whichfalls within the range from 0 to 999 which is defined as the range ofthe content ID of the browser content Cb.

Also, the content ID space manager 1501 adds information for defining acontent ID space to the service attribute information stored in theservice attribute information storage 111.

FIG. 20 shows exemplary service attribute information Isps. The contentsof the service attribute information Isps are the same as those of theservice attribute information Isp according to the first embodimentshown in FIG. 4. Specifically, the operation of activating the browsercontent Cbs in accordance with the present embodiment is basically thesame as the operation in accordance with the first embodiment describedwith reference to FIG. 9, except that the service attribute informationIsp is changed to Isps and the target content C is changed to thebrowser content Cbs. Accordingly, the description of the operation isomitted.

Next, referring to FIG. 23, an operation of updating the browser contentCbs by the non-storage type reception device 130 is described. As shownin FIG. 18, the operation of updating the browser content Cb inaccordance with the present embodiment is such that step S608 in theflowchart shown in FIG. 10 is replaced by steps S1801 and S1402.

Specifically, at step S1801, based on content C (Cn) demodulated and acontent header Hc separated at step S601, a search is conducted for acontent C in a selected service, which has a content ID falling withinthe range of the browser content Cbs designated by the service attributeinformation Isps. If any corresponding content C is found, the procedureproceeds to the next step S602. On the other hand, if no correspondingcontent C is found, the procedure returns to the above-described stepS601.

As described above, the non-storage type broadcasting system 1500manages the space for content IDs, so that a content having a content IDcorresponding to a specific value designated by the management can bedesignated as the browser content Cbs. In this manner, the browsercontent Cbs can be designated without preparing any specific field (inthis example, a column) in the content header HcBs, for example.

That is, if it is ensured that only the content provider stores thecontent body Dc corresponding to the service thereof into the contentstorage 113, whatever content C is stored in the content storage 113, itis possible to prohibit the browser content Cb from being incorrectlydesignated for a different service and being executed in the non-storagetype reception device 130.

In the present embodiment, if a single content ID space is provided forall of a plurality of service providers, it is possible to predeterminethe range of the content ID to be taken by the browser content Cb andthereby to prevent the browser content Cb from being incorrectlydesignated by the plurality of service providers. Only content ID fieldsmay be used without preparing new fields in content headers, forexample, therefore it is possible to readily use contentreception-related parts of a conventional non-storage type receptiondevice without significantly changing a conventional sending device.

While the invention has been described in detail, the foregoingdescription is in all aspects illustrative and not restrictive. It isunderstood that numerous other modifications and variations can bedevised without departing from the scope of the invention.

Where an existing broadcasting infrastructure is used to implementbrowser transmission in the non-storage type broadcasting system of thepresent invention, it is desired or required that signal format for thebroadcasting standard should be satisfied.

Reason 1: In digital broadcasting, it is prohibited to send radio wavesother than those in signal formats defined by law or standards.Accordingly, introduction of a new signal format does not meetrequirements of law or standards, therefore in the worst cases, thebroadcaster might be deprived of the license of broadcasting.

Reason 2: The introduction of a new signal format might causemalfunction of reception devices having been connected to thebroadcasting infrastructure. For example, the estimated life of adigital television set is about ten years. In this case, therequirements are not satisfied in that a currently receivable radiosignal does not cause malfunction of a television set which has beenshipped ten years ago.

Reason 3: The introduction of a new signal format entails significantcost in upgrading and testing broadcasting facility, and thus is notpractical.

Reason 4: If requirements about an existing broadcasting standard signalformat are satisfied, it is not necessary to provide an additional fixedband width for browser transmission in addition to a bandwidth fortransmitting signal content. That is, the same band is used for bothcontent transmission and browser transmission. Thus, it is possible toprevent the occurrence of the waste due to the use of different bandwidths between the content and browser, e.g., the band width isinsufficient for content transmission, while the bandwidth for browsertransmission is available. Further, it is not necessary to separatelyprepare a mechanism for managing the bandwidth for browser transmission.

Reason 5: If the requirements about an existing broadcasting standardsignal format are satisfied, it is possible to receive a browsersimultaneously with content. It is often the case that a typicalconventional reception device is able to receive only one broadcastchannel at a time under the constraint of cost, etc. The browser istransmitted on a channel different from that on which a televisionprogram (content) is being broadcast. Thus, a channel for transmittingthe browser is received in late-night hours during which no content isbeing received, and browser replacement is carried out. According to thepresent invention, in such a case, the same broadcast channel isreceived under the situation where a browser is desired at the verymoment of receiving content, whereby it is possible to immediatelyreceive the browser required for that content.

Reason 6: In the present invention, limited computation resources (ROMcapacity, RAM capacity, CPU processing speed) of a receiver can beeffectively used regardless of a new or existing signal format. If thetransmission scheme for the browser is the same as that for the content,it is meant that there is only one transmission protocol for the browserand the content.

In general, in order to implement a protocol stack, which is softwarefor receiving protocols, the ROM capacity for storing programs requiredfor processing for each protocol and the RAM capacity for theimplementation are required. In the present invention, there is only oneprotocol, and therefore the ROM and RAM capacities maybe slightlygreater than those of even a reception device which cannot update thebrowser. Further, overhead for switching between protocols is notrequired, therefore it is possible to simultaneously receive the browserand the content at about the same CPU processing speed.

Reason 7: In the present invention, the time to receive the content andthe browser is completely controlled based on the time at which thebrowser contained in the content is transmitted from the transmissionside regardless of a new or existing signal format. It is possible forthe transmission side to provide control such that the content is notsent out while the browser is being sent and thereby to prevent the loadon the receiver from increasing more than required. Also, by sending outa browser, which is required for presenting a specific content, at anappropriate time, it is made possible to ensure based on control by thebroadcasting side that a suitable browser has always been received uponreceipt of the content. The control does not require the computationresources of the receiver side.

Reason 8: In the present invention, only one-way data transmission froma sending device to a reception device is required for executionregardless of a new or existing signal format. Therefore, it isimplementable without requiring any communication infrastructure capableof transmitting any information to the sending device via an additionalcommunication line or the like. In the case where there are millions ofreception devices, even if it is necessary to replace browserssimultaneously, the sending device is only required to broadcastnecessary information. Thus, the implementation is relatively easybecause it is not necessary to prepare a server or a communication linefor accepting browser transmission requests from millions of receptiondevices.

INDUSTRIAL APPLICABILITY

Thus, the present invention is advantageous in a non-storage typeinformation service system which automatically provide the user inreal-time with a presenter required by the user for viewing a desiredcontent with a viewer.

1. A non-storage type broadcasting system (100) for providing one ormore services (S) composed of a content (C) in real-time for viewing bya user and providing a user interface (B) unique to each (Sm) of theservices (S), the system comprising: transmission means (110) forsending out a control content (Cb), which implements the user interface(B), as a part or whole of the content (C); and reception means (130)for receiving the sent control content (Cb) and activating the receivedcontrol content (Cb) to execute the user interface (B), wherein the userinterface (B) is transmitted/received as a content.
 2. The non-storagetype broadcasting system (100) according to claim 1, wherein the controlcontent (Cb) is a browser (B) for the content (C).
 3. The non-storagetype broadcasting system (100) according to claim 1, wherein thetransmission means (130) includes: content sending means (112) forsending out a content (C) containing the control content (Cbc); andservice attribute information sending means (111) for sending outservice attribute information (Isp) indicating details of the services,and wherein the reception means (130) includes control contentidentification means (S504) for identifying the control content (Cb)from among received contents (C) based on the received contents (C, Hc)and the service attribute information (Isp).
 4. The non-storage typebroadcasting system (100) according to claim 3, wherein the contentsending means (112) includes content header addition means (112) foradding, to the content (C), a content header (Hc) which defines detailsof the content, and wherein the reception means (130) identifies thecontrol content (Cb) from among the received contents (C) based oncontent headers (Hc) of the received contents (C, Hc).
 5. Thenon-storage type broadcasting system (700) according to claim 3, whereinthe transmission means (710) further includes electronic signature means(711) for applying an electronic signature to the control content (Cbc),wherein the service attribute information sending means (111) sends outa public key (KP) of the electronic signature (Sg) in the serviceattribute information (Isp), wherein the reception means (730) furtherincludes signature authentication means (138; S1002) for authenticatingthe electronic signature with the public key (KP) contained in receivedservice attribute information (Isp), and wherein the control content(Cb) is identified by authenticating the electronic signature.
 6. Thenon-storage type broadcasting system (700) according to claim 5, whereinthe authentication by the electronic signature (Sg) is performed using akey independent of each service.
 7. The non-storage type broadcastingsystem (1500) according to claim 3, wherein the content sending means(112) further includes content ID space management means for sending outinformation (CSD) which defines a partial space of an ID space of thecontent (C), and wherein the reception means (130) further includesidentification means (S1801) for identifying the control content (Cb)based on whether a content ID falls within the partial space.
 8. Acontrol content transmission method for use in a non-storage typebroadcasting system (100) for providing one or more services (S)composed of a content (C) in real-time for viewing by a user, the methodproviding a user interface (B) unique to each (Sm) of the services (S),the method comprising: a step of sending out a control content (Cb),which implements the user interface (B), as a part or whole of thecontent (C); and a step (S501-S505) of receiving the sent controlcontent (Cb) and activating the received control content (Cb) to executethe user interface (B).
 9. The control content transmission methodaccording to claim 8, wherein the control content (Cb) is a browser (B)for the content (C).
 10. The control content transmission methodaccording to claim 8, wherein the step of sending out further includes:a content sending step of sending out a content (C) containing thecontrol content (Cbc); and a service attribute information sending stepof sending out service attribute information (Isp) indicating details ofthe services, and wherein the reception step (S501-S505) includes acontrol content identification step (S504) of identifying the controlcontent (Cb) from among received contents (C) based on the receivedcontents (C, Hc) and the service attribute information (Isp).
 11. Thecontrol content transmission method according to claim 10, wherein thecontent sending step includes a content header addition step of adding,to the content (C), a content header (Hc) which defines details of thecontent, and wherein the reception step further includes a step ofidentifying the control content (Cb) from among the received contents(C) based on content headers (Hc) of the received contents (C, Hc). 12.The control content transmission method (700) according to claim 10,wherein the step of sending out further includes an electronic signaturestep (711) of applying an electronic signature to the control content(Cbc), wherein the service attribute information sending step furtherincludes a service attribute information sending step of sending out apublic key (KP) of the electronic signature (Sg) in the serviceattribute information (Isp), and wherein the reception step furtherincludes: a signature authentication step (S1002) of authenticating theelectronic signature with the public key (KP) contained in receivedservice attribute information (Isp); and a step (S1003) of identifyingthe control content (Cb) by authenticating the electronic signature. 13.The control content transmission method according to claim 12, whereinthe authentication by the electronic signature (Sg) is performed using akey independent of each service.
 14. The control content transmissionmethod according to claim 10, wherein the content sending step furtherincludes a content ID space management step of sending out information(CSD) which defines a partial space of an ID space of the content (C),and wherein the reception step further includes an identification step(S1801) of identifying the control content (Cb) based on whether acontent ID falls within the partial space.
 15. A reception device (130)for use in a non-storage type broadcasting system (100) for providingone or more services (S) composed of a content (C) in real-time forviewing by a user and providing a user interface (B) unique to each (Sm)of the services (S), the reception device receiving a control content(Cb) which implements the user interface (B), the control content beingtransmitted as a part or whole of the content (C) and having addedthereto service attribute information (Isp) indicating details of theservices, the reception device comprising: reception means (131) forreceiving contents (C) transmitted from a the transmitter (110);extraction means (132) for demodulating the received contents (C) andextracting the contents (C, Hc) and the service attribute information(Isp); and control content identification means (S504) for identifyingthe control content (Cb) from among the received contents (C) based onthe extracted contents (C, Hc) and the service attribute information(Isp).
 16. The reception device (130) according to claim 15, wherein inthe non-storage type broadcasting system (100), the content (C) istransmitted after being further added with a content header (Hc) whichdefines details of the content, wherein the extraction means (132)further extracts the content header (Hc) from the received contents (C),and wherein the control content identification means (S504) identifiesthe control content (Cb) from among the received contents (C) based onthe extracted content header (Hc).
 17. The reception device (730)according to claim 15, wherein in the non-storage type broadcastingsystem (700), the control content (Cbc) is signed with an electronicsignature, and a public key (KP) of the electronic signature (Sg) issent out in the service attribute information (Isp), wherein thereception device (730) further includes signature authentication means(138; S1002) for authenticating the electronic signature with the publickey (KP) contained in received service attribute information (Isp), andwherein the control content identification means (S504) identifies thecontrol content (Cb) by authenticating the electronic signature.
 18. Thereception device (730) according to claim 17, wherein the authenticationby the electronic signature (Sg) is performed using a key independent ofeach service.
 19. The reception device according to claim 15, wherein inthe non-storage type broadcasting system (1500), the content (C) isadded with information (CSD) which defines a partial space of an IDspace of the content (C), and wherein the identification means (S 1801)further identifies the control content (Cb) based on whether a contentID falls within the partial space.